1. Field of the Invention
The present invention relates to an information storage medium, such as an optical disk, on which information is recorded by radiating a light beam onto a recording layer to form a pit in the beam radiation portion, and from which information is reproduced by detecting a difference in optical characteristics between a pit portion and a non-pit portion, and a method of manufacturing the same.
2. Description of the Related Art
According to a known conventional information storage medium, in order to record information, a light beam is radiated onto a recording layer so that the beam radiation portion is melted or vaporized to form a pit.
A recording layer comprises a metal, semimetal, or semiconductor having a relatively low melting point, such as Te, so as to facilitate the formation of pits upon radiation of light beams (M. Chen and V. Marrello "The effect of overcoats on the ablative writing characteristics of tellurium films, J. Vac. Sci. Technol., 18(1), Jan./Feb. 1981).
An information storage medium having a recording layer containing carbon and hydrogen as well as Te is known (Japanese Patent Disclosure (Kokai) No. 58-9234). This information storage medium is advantageous in that carbon and hydrogen suppress oxidation of Te, which is susceptible to such, so as to allow additional data to be written on a recording layer which is stable over a comparatively long period of time
Such an information storage medium is formed by sputtering of Te target in Ar gas atmosphere, together with CH.sub.4 gas. Therefore, Te is dispersed in a matrix containing hydrocarbon in the resultant recording layer.
Even if the recording layer contains carbon and hydrogen through this operation, its stability, especially resistance to oxidation may degrade with the lapse of time. Even in such a case, the period over which recorded information retains its stability is often insufficient.